1. Field of the Invention
The present invention relates to a method and an apparatus for reclaiming and purifying used refrigerant. A primary field of application of the invention is the reclaiming of the refrigerant from small refrigeration units to be scrapped, e.g. household refrigerators and air conditioning units in abandoned cars, as well as the removal, purification and recharging of the refrigerant in connection with similar units still in operation.
2. Background of the Invention
As well known, refrigerants as known and used so far are considered dangerous for their ability to attack the stratospheric ozone layer, and it becomes increasingly required to eliminate or at least further minimize the amounts of refrigerant that are liable to escape into the air in connection with the processing of the reclaimed refrigerant. The processing may well take place in fully sealed systems, whereby purified refrigerant may be collected for renewed use, in general or by immediate recharging. However, it is almost inevitable that the purification gives rise to precipitation products that cannot be held isolated from the atmosphere, and generally the refrigerant will be well soluble in these products, whereby a minor fraction of the refrigerant will leave the sealed system and get exposed to the atmosphere anyway. The precipitation products, mainly, are oil and air or other non-condensable gases.
Oil is present in the refrigerant as a result of the serviced refrigeration system normally comprising a compressor that has to be lubricated. In normal operation the oil present in the compressed gaseous refrigerant will be precipitated in an oil separator and returned to the compressor, but still an operationally acceptable, small amount of oil will remain in the gas phase of the refrigerant and in the remaining circuit thereof, i.e. in the liquid phase as produced by a following condenser and then again in the gaseous phase as produced by an associated evaporator prior to the gaseous refrigerant being returned to the suction side of the compressor. When the refrigerant is drawn out of the unit for evaporation into the discussed processing system this residual oil will be drawn out as well, and inevitably it will contain a certain amount of dissolved refrigerant.
The refrigerant is transferred from the operative unit to the processing equipment by connecting a suction side of a compressor in the latter equipment to an accessible point of the refrigeration circuit of the former unit, whereby at least most of the refrigerant of that unit will evaporate and be sucked over to the processing equipment, however accompanied by the associated oil contents. The design of some refrigerant circuits will even allow liquid refrigerant mixed with the oil to enter the processing equipment. The processing equipment may be equipped with an oil separator for precipitating the oil, but the precipitant may still hold a considerable amount of dissolved refrigerant, which may thus escape into the air outside the closed system, when the contaminated oil is collected in an external system for disposal.
As mentioned, another contamination source will be the air or other non-condensable gases precipitated at the pressure side of the compressor of the processing system, as discussed in commonly assigned copending U.S. application Ser. No. 762,009. The transferred gas almost inevitably will contain some atmospheric air that will have to be precipitated from the closed system, but any such amount of air will inevitably hold a certain amount of the dangerous refrigeration gas, which will be released to the atmosphere along with the collected air, once the gas has been recycled and purified.